The broad goals of this proposal are to evaluate the benefits of an academically-focused preschool curriculum on the school readiness skills and subsequent academic achievement of children who are Spanish-speaking English-language learners (ELLs) and to evaluate the benefit of delivering the curriculum to children using two variations of language of instruction. The project involves a 5-year cluster-randomized study that will compare outcomes for 1296 children enrolled in 108 preschool classrooms in multiple sites in CA, FL, KS, and NM who are exposed to one of three types of early childhood curricula: (a) A business- as-usual group (i.e., schools that continue to employ the curriculum currently in use), (b) A standard implementation of the Literacy Express Preschool Curriculum in English-only, and (c) A modified Two-Way bilingual implementation of the Literacy Express Preschool Curriculum adapted specifically for Spanish- speaking ELL children. The specific aims are to determine: 1. whether a high quality school readiness curriculum will significantly increase ELL children's academic performance in literacy and math; 2. whether children's socio-emotional development differs as a function of classroom curricula; 3. whether variations in the language of instruction significantly affect the impacts of the curriculum on children's school readiness outcomes in literacy, math, and socio-emotional development, and 4. to examine classroom, teacher, child, and family factors that may potentially moderate the efficacy of the curriculum for children's literacy and math skill development. Children will be followed longitudinally and assessed near the end of their kindergarten and 1st grade years to estimate the longer-term impacts of the three curriculum conditions on academic skills in reading and math, and on socio-emotional outcomes. Spanish-speaking ELL preschool children are at high risk for school failure. The proposed intervention and the anticipated positive outcomes have the potential to reduce the incidence of the negative sequelae associated with low school readiness skills of children who are Spanish-speaking ELLs and to increase their chances of high academic success in reading, math, science and socio-emotional functioning in kindergarten and beyond.